Over time, basic research tends to lead to specialization - increasingly narrow t- ics are addressed by increasingly focussed communities, publishing in increasingly con ned workshops and conferences, discussing increasingly incremental contri- tions. Already the community of programming languages is split into various s- communities addressing different aspects and paradigms (functional, imperative, relational, and object-oriented). Only a few people manage to maintain a broader view, and even fewer step back in order to gain an understanding about the basic principles, their interrelation, and their impact in a larger context. The pattern calculus is the result of a profound re-examination of a 50-year - velopment. It attempts to provide a unifying approach, bridging the gaps between different programming styles and paradigms according to a new slogan - compu- tion is pattern matching. It is the contribution of this book to systematically and elegantly present and evaluate the power of pattern matching as the guiding paradigm of programming. Patterns are dynamically generated, discovered, passed, applied, and automatically adapted, based on pattern matching and rewriting technology, which allows one to elegantly relate things as disparate as functions and data structures. Of course, pattern matching is not new. It underlies term rewriting - it is, for example, inc- porated in, typically functional, programming languages, like Standard ML - but it has never been pursued as the basis of a unifying framework for programming.

Over the past few years there have been considerable advances in our understanding of the normal development of vision and in our ability to detect and meaSl1re visual impairment in early childhood. It was appropriate, therefore, that a workshop, sponsored by the European Communities, should be held on the 'Detection and Measurement of Visual Impairment in Pre-verbal Children.' This workshop, which was held at the Institute of Ophthalmology, London, between 1 and 3 April 1985, brought together visual physiologists and ophthalmologists who exchanged and discussed ideas of mutual interest. After an introductory session when the normal development of vision and the causes of visual impairment were reviewed, there were sessions devoted to the theoretical aspects of electrophysiological and psychophysical tests, the measurement of visual acuity in pre-verbal children, the measurement of other visual functions, and visual screening of pre-verbal children. This volume contains the papers presented at the workshop, and transcripts of the various discl1ssions that took place. It was a measure of the success of the workshop that participants from several different disciplines were able to have fruitful discussions and to suggest areas of common interest where collaborative ventures could usefully be pursued. It is hoped that this venture will be followed by others where a mul ti disciplinary approach will improve both our knowledge of visual handicap in childhood and our management of this important group of sensorily impaired children."

Over time, basic research tends to lead to specialization - increasingly narrow t- ics are addressed by increasingly focussed communities, publishing in increasingly con ned workshops and conferences, discussing increasingly incremental contri- tions. Already the community of programming languages is split into various s- communities addressing different aspects and paradigms (functional, imperative, relational, and object-oriented). Only a few people manage to maintain a broader view, and even fewer step back in order to gain an understanding about the basic principles, their interrelation, and their impact in a larger context. The pattern calculus is the result of a profound re-examination of a 50-year - velopment. It attempts to provide a unifying approach, bridging the gaps between different programming styles and paradigms according to a new slogan - compu- tion is pattern matching. It is the contribution of this book to systematically and elegantly present and evaluate the power of pattern matching as the guiding paradigm of programming. Patterns are dynamically generated, discovered, passed, applied, and automatically adapted, based on pattern matching and rewriting technology, which allows one to elegantly relate things as disparate as functions and data structures. Of course, pattern matching is not new. It underlies term rewriting - it is, for example, inc- porated in, typically functional, programming languages, like Standard ML - but it has never been pursued as the basis of a unifying framework for programming.